1. Field of the Invention
This invention relates generally to folding, collapsible structures, and more particularly relates to a collapsible shelter structure having an elevated canopy.
2. Description of Related Art
Temporary shelters that can be easily transported and rapidly set up at emergency sites can be particularly useful in providing temporary care and housing. Such shelters can also be useful for non-emergency outdoor gatherings, such as for temporary military posts, field trips, and the like. One known quickly erectable, collapsible shelter includes a framework of X-shaped linkages, telescoping legs, and a canopy covering the framework. The legs of that shelter are capable of telescoping to about twice their stowed length, and the framework of X-shaped truss pairs is capable of horizontal extension between the legs to support a canopy. The framework can be constructed of lightweight material, and the telescoping legs can be extended to raise the framework of the shelter.
In order to increase the portability and versatility of such temporary shelters, it is important that they be not only lightweight and small enough in a folded, compact configuration so that can be readily transported and carried, but also large enough and with sufficient headroom when unfolded for a group of people to stand underneath them. As such structures have become larger and more lightweight, reinforcing features that contribute to strength, roominess, and ease of use in setting up and taking down such structures have also become increasingly important.
One modern type of tent structure provides a lightweight roof structure with four roof rods joined together at the center by a head connector member, with each of the roof rods formed of two rod members interconnected by intermediate pivot connecting members. The roof rods are supported on top of a base structure formed by four legs and scissors-type linkages connected to a top fixed connector and a lower sliding connector of each leg. Each intermediate pivot connecting member between the individual rod members of the roof rods confines upward rotation of the rod members to an upmost, upwardly arching position, but allows the roof rods to be folded downwardly when the tent is collapsed. Reinforcing linking rods provided at the corners of the roof structure are coupled at one end to the lower sliding connectors on the legs, and are slidingly coupled at the other end to the roof rods, to assist in stabilizing the roof rods in the upwardly arched position when the shelter is fully unfolded and extended. However, the slidable coupling of the corner linking rods must slide over a considerable length of the roof rods, which can lead to abrasion and wear of the roof rods and eventually interfere with the sliding of the linking rods during setting up and taking down of the structure, without providing any significant reinforcing strength or vertical support of the roof structure when the shelter is fully unfolded and extended.
Lightweight shelters with raised roof structures are particularly useful for holding gatherings in inclement weather, to provide needed headroom and shed precipitation and debris, but raised roof structures can be particularly vulnerable to downward forces placed on a roof structure by strong winds. One approach to providing a lightweight shelter with a raised roof structure has been to make the roof structure flexible so that it can move between a raised, upwardly arching configuration when weather permits, and a lowered, downwardly arching configuration, if the downward component of the wind is sufficiently strong, to automatically present a reduced profile to strong winds when necessary. However, in some shelter structures, a downward force on the canopy, such as can occur due to wind pressure, for example, can result in the transmission of excessive outward forces to the upper legs and upper brackets to which the roof structure is mounted, requiring extra strengthening or bracing of these sections of the shelter to resist such outwardly directed forces. There thus remains a need for an improved, reinforced raised roof structure for such lightweight canopy shelters that will permit the raised roof structure to withstand greater wind pressures, to be able to provide a desired headroom and shed precipitation and debris under a wider variety of weather situations. The present invention meets these and other needs.